VOLVO
ECM-2100 - Front heated oxygen sensor (HO2S). Current too low. Intermittent fault
System
Engine Control Module (ECM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
7 modelsC70 Cabriolet (1998–2005), C70 Coupé (1998–2002), S60 (2001–2009), S70 (1997–2000), S80 (1999–2006), V70 (1997–2000), V70 (2000–2008)
Show models by year and engine (14)
- Volvo C70 Cabriolet (1998–2005)2000Engine B5244S only
- Volvo C70 Coupé (1998–2002)1999Engine B5254S DENSO only
- Volvo C70 Coupé (1998–2002)2000Engine B5244S only
- Volvo S60 (2001–2009)2001Engine B5244S, B5244S2 only
- Volvo S60 (2001–2009)2002Engine B5244S, B5244S2, B5244SG, B5244SG2 only
- Volvo S70 (1997–2000)1999Engine B5254S DENSO only
- Volvo S70 (1997–2000)2000Engine B5244S, B5244S2, B5244SG, B5244SG2 only
- Volvo S80 (1999–2006)1999–2000Engine B5244S, B5244S2 only
- Volvo S80 (1999–2006)2001Engine B5244S, B5244S2, B5244SG only
- Volvo S80 (1999–2006)2002Engine B5244S, B5244S2, B5244SG, B5244SG2 only
- Volvo V70 (1997–2000)1999Engine B5254S DENSO only
- Volvo V70 (1997–2000)2000Engine B5244S, B5244S2, B5244SG, B5244SG2 only
- Volvo V70 (2000–2008)2001Engine B5244S, B5244S2, B5244SG only
- Volvo V70 (2000–2008)2002Engine B5244S, B5244S2, B5244SG, B5244SG2 only
What does this fault code mean?
The fault is registered as intermittent, meaning it occurred at some point but may not be present now. The engine control module (ECM) has registered that the current from the front oxygen sensor is too low. The fault may be caused by a connector that is only occasionally making poor contact.
Possible causes
- Signal wire short-circuited to supply voltage
- Defective front oxygen sensor
- Occasional poor contact in the connector at the sensor
What you can do
- 1Read and clear the fault code and check whether it returns
- 2With the ignition on, gently move the connector at the front oxygen sensor and see whether the fault follows
- 3Check the connector for contact resistance and oxidation, and do not use penetrating spray or grease in it
- 4Check the wire for chafing and for short circuits to supply voltage
- 5If the fault returns, have a workshop check the oxygen sensor
Symptoms you may notice1
- No noticeable symptoms for the driver
What the fault can affect1
- Fuel trim control is switched off
General guidance for car owners. Diagnosis on the car can point to a different cause.